Blow torch



Jan. 2, 1934'. F. T, POTTER 1,941,755

BLOW TORCH Filed Nov. 2, 1 93 III! z fiezkz 'zzfr @WMMV writ Patented Jan. 2, 1934 UNlTED STATES PATENT OFFICE BLOW TORCH Application November 2, 1931. Serial No. 572,499

2 Claims.

This invention relates to blow torches and its object is to provide an electrically operated portable blow torch which may be used with various types of gaseous fuels and which is highly eflicient in operation. Other objects relate to its construction and operation and will be apparent from a consideration of the following description and the accompanying drawing, in which Fig. 1 is a top plan view or" the blow torch;

Fig. 2 is a side elevation, partly in section and with parts broken away; and

Fig. 3 is a section on the line 3--3 of Fig. 2.

The particular embodiment of the invention chosen for the purpose of illustration comprises 15 a base 1 having an integral upstanding bracket 2 to which the depending lug 3 of the cylindrical casing 4 is pivotally connected. By means of a bolt 5 passing through registering openings in the lug and bracket and a wing nut (not shown), 20 the casing may be tilted and clamped in any desired position. The front end of the casing is provided with an air inlet, here shown as an S- shaped slot 6, and a noselike discharge duct '7 on its periphery.

A motor 8 is mounted on the opposite end of the casing with its shaft projecting through a central opening therein. Preferably the motor is of a high speed type adapted to rotate about 8500 R. P. M. and is provided with a toggle switch 9 which may be conveniently located on the top of the casing as shown in Fig. l. A centrifugal fan 10 is mounted on the shaft within the casing, air being drawn in through the inlet 6 and discharged at a high velocity through the duct '7.

The air flow is controlled or regulated by a valve 11 which, as shown in Fig. 3, comprises a. stem 12 disposed in a vertically extending opening 13 in the discharge duct. The stem 12 is provided with a transverse opening 14 which registers with the opening in the discharge duct when in open position, and a thumb piece 15 by means of which the stem may be turned 90 in either direction completely to close the discharge duct. A set screw 16 engages a circumferential groove 17 in the lower end of the stem and not only prevents vertical movement thereof but also provides means for locking the valve in adjusted position.

The delivery end of the discharge duct '7 has an enlarged bore in which the end of the burner nozzle 20 tightly fits. The nozzle 20 has an opening 21 adjacent to its end, the opening registering with a gas inlet 22 which communicates with the discharge duct 7 and is arranged to deliver gas directly into the nozzle wherein the gas and air are mixed. The gas supply pipe 23 is provided with a pet-cock or valve 24 which serves to connect the gas inlet 22 with the supply pipe and by means of which the gas supply is regulated. Although the length of the nozzle may vary between certain limiting conditions, it is essential that it shall be long enough to permit the gas and air to become thoroughly mixed; otherwise satisfactory results can not be depended upon. I have found that a nozzle having a five-inch length and threeeighths to one-half inch bore is very efficient when used with a high speed blower.

The outer end of the nozzle is provided with a pilot tip 25 which comprises radially spaced concentric flanges 26 and 27 defining an annular recess therebetween. The inner flange 26 has a pressed fit about the end of the nozzle and is provided with a plurality of circumferentially spaced apertures 28 which provide a communication between the nozzle and the annular recess. A very small part of the gas mixture passing through the nozzle escapes to the recess where it burns with an annular flame which surrounds the inner flange, thus keeping the main jet lighted and also preventing objectionable flickering which ordinarily results from the use of relatively high velocity jets.

A blow torch constructed in accordance with my invention may be used with various gaseous fuels including such types as natural gas which ordinarily can not be used in high velocity jets. The gas and air control valves make it possible not only to regulate the proportions of the mixture, but also the size of the flame which may be varied from a relatively long brush to a short sharply-defined needlepoint flame.

While I have shown and described one desirable embodiment of the invention, I wish it to be understood that various changes in shape, proportion and arrangement of parts, as Well as the substitution of equivalent elements for those herein illustrated and described, may be used without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. A portable, self-contained blow torch, comprising a substantially cylindrical casing having an air intake in one end, and a tangentially disposed discharge duct on its periphery, a centrifugal fan within said casing, an electric motor for driving said fan mounted on the opposite end of said casing, a valve in said discharge duct for regulating the air flow therethrough, a gas supply pipe communicating with said discharge duct intermediate said valve and the outer end of the duct, said supply pipe being arranged to deliver gas into said duct at substantially right angles to the line of travel of air therethrough, a valve in said pipe for regulating the gas flow therethrough, an elongate burner nozzle rigidly secured to said casing in axial aligmnent with said discharge duct, said nozzle constituting a mixing chamber for the gas and air, and a pilot tip comprising radially spaced concentric flanges defining an annular; recess therebetween, the inner flange adjoining the end of the nozzle and having a plurality of circumferentially spaced apertures providing a communication between the nozzle and said annular'recess.

2. A portable, self-contained blow torch, comprising a substantially cylindrical casing having an air intake in one end and altangentially extending nose-like member on its periphery providing an outwardly tapering discharge duct, said member having a socket-like recess intersecting said discharge duct, a centrifugal fan within said casing, an electric motor for driving said fan mounted. on the opposite end of said casing, a

Vvalve member seated in said socket-like recess ':for regulating the air flow through said discharge duct, a gas supply pipe communicating with said discharge duct intermediate said valve and the outer end of the duct, said supply pipe being arranged to deliver gas into said duct at substantially right angles to the line of travel of air therethrough, a valve in said pipe for regulating the gas flow therethrough, an elongate burner nozzle rigidly secured to said nose-like member and disposed in axial alignment with said discharge duct, said nozzle constituting a mixing chamber for the gas and air, and a pilot tip comprising radially spaced concentric flanges defining an annular recess therebetween, the inner flange adjoining the end of the nozzle and having a plurality of circumferentially spaced apertures providing a communication between the nozzle and said annular recess.

FREDERICK T. POTTER. 

